Apparatus for stoking furnaces



April 20, 1937. H. L, KRAEFT 2,077,420

APPARATUS FOR STOKING FURNACES Filed Jan. 4, 1933 5 Sheets-Sheet 1 April 20, 1937. H. KRAEFT 2,077,420

APPARATUS FOR STOKING FURNACES Filed Jan. 4, 1933 5 SheetsSheet 2 w @am,-WJ/LM G ttmmy April 20, 1937. H. L. KRAEFT APPARATUS FOR SIOKING FURNACES Filed Jan. 4, 1933 5 Sheets-Sheet 3 April 20, 1937. H. L. KRAEFT.

APPARATUS FOR STOKING FURNACES Filed Jan. 4, 1935 5 Sheets-Sheet 4 April 20, 1937. H.'l KRAEFT 2,077,420-

APPARATUS FOR STOKING FURNACE S Filed Ja n. 4, 1953 5 Sheets-Sheet 5 EZC+8- M 5.: 1: 1 ma /Z5 Z/ZZE l l atented Apr. 20, 1937 UNITED STATES PATENT OFFICE APPARATUS FOR STOKING FURNACES Application January 4, 1933, Serial No. 650,095

7 Claims.

This invention is concerned with a stoker mechanism primarily adaptable for overfeed stokers, and particularly to overfeed stokers for domestic heating furnaces, and to carry out my 5, method of fueling a furnace described in my Patent No. 2,027,485 issuedJanuary 14, 1936, and

of which this application comprises a continuation in part.

The general object of the present invention is the provision of a coal stoking mechanism which will be readily adaptable to various types of domestic furnaces, and which will be efficiently responsive to the functioning of thermostatic controls while being utilizable for the feeding of a 1.3 wide range of fuels. To this end the present invention is concerned primarily with a stoker mechanism adaptable to the stoking of vapor, steam and hot air domestic furnaces, regardless of the variations in the design of the furnace 20 structure and dimensional variations in the fireboxes of such furnaces. The invention embodies a mechanism which can be quickly and readily installed in cooperative relation with a furnace without necessitating any serious alterations in the furnace structure.

A further object of my invention is the provision of a stoker mechanism which will function in such manner as to eliminate the danger of fire hazards.

30 A still further object of my invention is the provision of a compact stoker mechanism which may be easily and quickly brought into cooperative relation with the fire door of the furnace v structure or be removed therefrom manually and 3.; without requiring any disorganization of the elements comprising the stoker mechanism.

A still further object of my invention is the provision of a stoker mechanism having a fuel agitating hopper which will prevent arching of lo the fuel while in the hopper.

A further objectis the provision of an improved overhead suspension for a stoker mechamsm.

Other objects and purposes of my invention, as

. embodied in the mechanism shown in the drawings, will hereinafter become apparent from the following description, which refers to said drawings and the essential objects of the invention are summarized in the claims.

50 In the drawings, Fig. 1, is a side elevation of a domestic heating furnace of the hot air type, showing my stoker mechanism associated therewith, certain parts of the furnace being broken away to more fully illustrate the stoker mecha- 55 nism; Fig 2, is a perspective view of the stoker mechanism, removed from association with the fire door of the furnace; Fig. 3 is an enlarged front elevation of part of the furnace and stoker mechanism shown in'Fig. 1, certain parts being broken away to illustrate the internal construction thereof; Fig. 4, is a fragmentary longitudinal sectional elevation through part of the stoker mechanism in cooperative relation with the fire door of the furnace, the plane of the section being indicated by the offset line 44 of Fig. 3; Fig. 5 is a fragmentary horizontal section through part of the stoker mechanism, taken substantially along the line 5-5 of Fig. 4; Fig. 6, is a sectional view taken substantially along the line 6-6 of Fig. 4; and Fig. '7 is a sectional view of a speed reducing device comprising part of the stoker drive; Fig. 8, is an enlarged view of a damper mechanism, certain parts thereof being broken away to more clearly illustrate the internal construction; Fig. 9 is a section taken along the line 9--9 of Fig. 8; Fig. 10 is a section taken along the line Ill-l0 of Fig. 9; Fig. 11 is an enlarged section taken substantially along the line I l--|l of Fig. 1 illustrating my improved manner of stoker suspension. I My invention is shown as being embodied in a unitary stoker and blower mechanism, which may be suspended by an overhead trolley, whereby the fuel discharge end of the stoker mechanism may be inserted in theme door of the furnace or withdrawn therefrom by shifting the stoker mechanism along a supporting trolley rail. The stoker mechanism is provided with a revolving hopper of a'substantial size, whereby a sufficient mass of fuel may be charged into the stoker to provide for-about a twelve-hour fuel demand of the furnace during the very cold season.

In Fig. 1, I show a hot-air furnace l0, provided with the usual fire door frame ll, fire pit I2 and ash pit l3. 'The stoker mechanism com- 40 prises a substantially large coniform hopper l5, revolubly mounted upon a downwardly extending coal guiding chute in the form of a neck or base I6, which supports the hopper IS with the axis thereof oblique to a horizontal plane. The base 4 I6 is round at the top and of a rectangular shape at the bottom, and'comprises a connecting passage way between the bottom opening of the hopper I5 and a rectangularly shaped fuel feed tube 45, attached to the bottom of the base l6. 5 To support the hopper, the base l6, (see'Figs. l, 3, 4 and 11) is provided with an annular outwardly extending flange H, to which is attached a suspension frame comprising a pair of downwardly extending bars I8 and a pair of arcuately shaped bars I9, a hopper bearing bracket 2| and straps 22. The bars I8, and I9 are attached at their upper ends to a trolley 23, by adjustable bolts 24 and 25, respectively. In Fig. 11, I show associated with the stoker supporting mechanism, and particularly with the bolts 24 and 25, means for absorbing all vibration incident to the operation of the stoker when the stoker mechanism is in use. This means is illustrated in the form of resilient cushions which take the entire weight of the stoker mechanism while the stoker is movably supported from a rail 30. The rail is suspended by strap members 26, which, at their lower ends are secured to the rail 30, while at the upper ends thereof, suitable hanger formations are provided for engagement with bolts 21. The upper ends of the bolts 21 are surrounded by resilient sleeves 28, preferably rubber. These sleeves bear against brackets 29, which are connected in any suitable manner to the ceiling structure. In similar manner I provide resilient sleeves 32, surrounding the upper ends of the bolts 24 and 25, and bearing upon the lower ends of suitable trolley wheel brackets 4|, that are secured in spaced relation by the trolley 23. The upper ends of the brackets 4|, extend over the rail 30 and sup port trolley wheels 42. I prefer to mount the rail 30 substantially horizontal and through adjustment of bolts 21, the inner end of the rail 30, that is, the end of the rail toward the furnace, is then dropped slightly below the opposite end, whereby the rail slopes toward the furnace, thus causing the stoker mechanism to have a tendency to remain in a forward or cooperating-position relative to the firebox door. By reason of the resilient suspension described, the entire mechanism may I be slightly swayed in manipulating the stoker mechanism relative to the firebox door. I provide the trolley mechanism with a locking lever 44, so arranged that the lever may be swung into a cammingor looking engagement with the rail to hold the stoker mechanism in a remote position from the furnace when it is desired, to inspect the firebox of the furnace.

I will now describe my manner of revolubly mounting the hopper, and particularly the con.-

struction of the lower end of the hopper. As

shown in Fig. 4, the lower end of the hopper is provided with an annular outwardly extending flange 35, positioned slightly above the flange I1.

The flange 35 comprises both a bearing plate for the lower end of the hopper and part of the mechanism which permits an intermittentrevolving movement of the hopper when the feed plunger is in motion. To decreasethe attendant friction I provide, as shown in Fig. 3, flanged rollers 31, which engage the flange 35. These rollers are spaced substantially ninety degrees apart, and are supported by stud bolts 38, 'fixed to the flange I1. These bolts also serve to rigidly secure the lower ends pf the straps 22, and bars I8, to the flange I1. The hopper bearing bracket 2| is provided with two spaced-apart rollers 2|a., which bear against a bearing band I5a, secured to the hopper wall. It will thus be apparent that the hopper I5 is supported upon six rollers, namely two rollers 2 la, and four rollers 31.

The fuel feeding mechanism comprises the rectangular tube 45, which is attached to and supported by the base IBin any suitable manner. Disposed within the tube and slidably arranged therein is a rectangular plunger 46, which is arranged to rest immediately beneath the outer edge of the base I6. The plunger 46 is provided with a bracket 48, having a wrist pin, the wrist pin being engaged by the inner end of a fork'shaped connecting rod 50. The outer end of the connecting rod 50 is operatively attached to a crank 5| carried by rotatable disc 52. The disc 52 is mounted upon the end of a gear shaft 53, whereby rotation of the shaft will cause a reciprocating movement of the plunger 46 within the feed tube 45. The travel of the plunger is dependent upon the radial displacement of crank 5| relative to the center of the shaft 53.

The shaft 53 comprises part of a'gear reduction mechanism housed, within a casing 54, the

casing being attached to the outer end of the feed tube 45.

The gear reduction mechanism is best shown in Fig. '1 and comprises an internal gear I40, secured to the casing 54, in cooperative relation with a gear .I4I, which is loosely mounted upon an eccentric I42, comprising part 'of a driving shaft I43. The driving shaft I43 is driven by a pulley 11. The gear I4I has attached thereto a spur gear I46, which meshes with an internal gear I41, fixed to a spider I48. The spider I48 is fixed to the driven shaft 53 by a pin I48, extending therethrough. The ratio between the gears I40 and MI is forty-one to forty-three respectively, and the, ratio between the gears I41 and I46 is forty to forty-two respectively. The rotation of the shaft I43 causes the double gear I4|--I46 to have a slight eccentric motion relative to the axis of the shaft I43, thus causing the gear |4I to have a one tooth displacement relative to the fixed internal gear I46 upon each revolution of the shaft I43. The gear I46, by reason of the fact thatit is fixed to-the gear I4I, thus 2 drives the internal gear I41 and shaft 53. The shafts 53 and. I43 may be supported with suitable bearings. To reduce frictional losses I provide a ball bearing mounting I60 and a sleeve bearing |6| to support the shaft I 43-, the sleeve bearing |6| being mounted in a suitable bore, formed in the inner end of the shaft 53. Bearings I64 and I65 serve to rotatably support the shaft 53 and v the attached spider I48. Adjustment\of the crank pin 5| relative to the center of the shaft 53 to vary the stroke of the plunger, is afiorded by the fact'that the crank pin has the crank end thereof eccentrically formed relative to the threaded bolt portion 5Ia thereof (see Fig. '1). A clamping nut 5|b serves to secure the pin 5| in position upon the disc 52 when the desired adjustment of the plunger stroke has been obtained. It should be noted that in Fig. '1 I providethe pin 5| with a knob 56 to facilitate adjustment of the pin. In the embodiment illustrated the stroke of the plunger may be varied from one inch to one and one-half inches.

In Fig. 4 I have shown a tray 58, which is slidably supported by transversely disposed guides 59, mounted on the bottom wall of the feed tube 45, adjacent a slot 6|! which extends substantially across the bottom wall of the tube immediately adjacent the outer edge 46a of the ,lower part, of the plunger structure, whereby any coal dust which becomes lodged along the side and bottom walls of the plunger will escape into the tray 58. The slidable mounting of the tray permits removal of such dust "from time to time.

face of the plunger 46, a fuel agitator which rides along the bottom wall of the tube 45, for substantially its entire fuel conducting length. This agitator comprises a metallic feeder 60,

.I arrange, at. the forward or fuel engaging provided with a series of transverse strips or teeth 8|, shaped to simulate ratchet teeth, whereby, upon the forward fuel feeding movement of the plunger 45, the teeth 8i engage the lowermost particles of the fuel and thus tend to move the entire column of fuel within the conduit. The feeder 80 covers substantially onethird of the area of the bottom wall of the tube and as the plunger moves forwardly assists the plunger in shifting the column of fuel forwardly. By reason of the shape of the teeth 8| the feeder has little tendency to move the coal rearwardly upon the return stroke of the plunger. The feeder and the coal thereon are supported by the bottom wall of the tube 45, to which end I provide a loose connection between the plunger and the feeder 80. Such connection may comprise vertically extending plates 50a secured to the plunger face, and loosely engaging flanges 82a formed on a bracket 82 comprising part of the feeder 80.

The mechanism for intermittently moving the hopper will now be described. The hopper I is revolved by a pawl 84, pivotally attached at its outer end to a bracket 05, rigidly secured to the connecting .rod 50 at such operative position that the pawl 84 may extend upwardly and outwardly to engage, in step by step movements, openings 25a, equidistantly spaced in the hopper flange '25. It will be apparent from Figs. 3 and 4 that revolving motion is imparted to the hopper during the return stroke of the plunger; thus voids momentarily created in the feed tube 45 by reason of the forward fuel stroke of the plunger will be eliminated by the agitation of the body of fuel upon the return stroke of the plunger. A detent pawll'l is provided at the opposite side of the flange 25 for preventing reverse movement of the hopper.

A fuel flipper mechanism is disposed at the extreme forward or discharging end of the fuel feeding tube 45 and is arranged within a housing, whereby, when the entire stokermechanism is shifted to operative position relative to the fire door, the flipper mechanism, while being disposed immediately adjacent the front wall of the fire box. will be protected by the housing. The proportioning' and design of the flipper mechanism is such that large particles of fuel cannot become lodged inany part of the mechanism which is exposed to the heat of the fire. The arrangement is also such that the stoker mechanism is readily adaptable to various sizes of fire door frames, which fire door frames may vary from 9 to inches. in length and from 8 inches by 10 inches in height and breadth respectively. The mounting of the flipper housing-is such that regardless of the width of the flredoor frame of the furnace the rotary'flipper member can always be adjusted to a juxtaposed position relative to the flre bed edge.

This fuel flipper mechanism comprises a revolving cylinder or flipper 10 (Figs. 4, 5, and 6) mounted upon a shaft I2. The shaft 12 has a sprocket wheel 13 mounted on an extending end thereof, and this sprocket wheel is driven by a suitable chain II. The chain II is driven by a sprocket wheel l secured to a rotatable sleeve 202, which is mounted upon an adjustable stud shaft 200. They sleeve 202 has also mounted thereon, a steppulley 204, driven by a belt 205, which belt is driven by a step pulley I32 mounted upon a motor shaft I24. The stud shaft 200 is adjustable to permit adjustment in the length of the feed tube, and thereby meet varying installation conditions, and to enable the rotary flipper I0 to be disposed adjacent the edge of the flrepit within the flredoor frame of the furnace. Accordingly, as shown in Figs. 4 and 5, I provide an arcuate slideway formation for adjusted anchorageof the stud shaft 200, upon the side wall of the feed tube. This anchorage may comprise a plate 208, to which the inner head 200a of the stud shaft may be clamped by a nut 206. Thus the shaft can be adjusted to swing its center about the center line of the motor shaft I24, should the length of the feed tube be increased or decreased to meet installation conditions. It will be apparent that two different feeds of the flipper 10 are obtainable through the step pulleys I32 and 204, and other feed changes may be made by changing the size of the sprocket wheel 13.

The flipper I0 is of substantially the same length as the width of the fuel tube 45 and the surface design thereof is of a particular functioning shape to be described in greater detail hereinafter, and is provided with an enclosing casing comprising an arcuately formed guard I4, having end walls 15 to which are attached bearings I5 for rotatably supporting the shaft 12 and flipper cylinder 10 in an operative position adjacent to and immediately below the inner discharge end of the feed tube 45. To support the casing comprising the guard for'the flipper 10, I provide a box-shaped housing 90, arranged to telescope with asecond box-shaped housing 9|, the latter being secured to a door closure plate 92 formed of any suitable material. The closure plate may be of such dimension as to comprise a closure for the largest size doors to be found on domestic furnaces of whatever type. The side walls 15 of the flipper casing are flanged, as indicated at 98 (Fig. 5) for rigid attachment to the housing, and the width and height of the housing 90 is such as to provide sufflcient space for the enclosure of the sprocket wheel 13, as well as the bearings I6. The side walls 15 of the flipper casing extend upwardly and are attached to a plate 01, which is flanged at the outer edge thereof for attachment to the housing 90 as shown at 90 (Fig. 4). The plate 91 is inclined downward and forward from the top wall of the housing 90 to serve as a fuel guide to deflect downwardly any heavier particles of fuel which might be flipped upwardly at too great an angle to escape the inner edge 95 of the fire door frame. The inner portion 91a of the plate 91 engages the top outer surface of an extension tube, I00, which comprises the inner portion of the fuel feed tube 45. The top wall 900. of the housing 90 extends between the portion 91a of the plate 51 and the top wall 9Ia of the telescoping housing 9|. The tube I00 is shaped to telescopically embrace the outer surfaces of the inner end of the tube 45, whereby the tube I00 may be of any desired length to suit the particular requirements of the installation. I provide bolts IOI for securing the tube I00 firmly to the inner end of the tube 45. I also provide the housing 90 with binding lugs and wing nuts, as indicated at I02, which lugs extend through slots I04 and I05 formed in the side walls of the housing 8|, and clamp the housings 90 and III firmly together in any adjusted position. I

I also provide an adjustable horizontally disposed ledge IIO, which in function comprises an extension of the bottom wall of the fuel feed tubes l5 and I00. This ledge I I0 serves to predetermine the falling movement of the coal particles as the same escape thereover upon the revolving flipper III. The ledge as shown in Fig. 4 is provided with downwardly extending slotted flanges IIOa through which clamping bolt III extends to secure the ledge in any desired adjusted position. Graduations, as indicated at II2 may be provided on one of the end walls I5 of the flipper casing to indicate the degree of adjustment of the ledge III) relative to a vertical plane extending through the axis of the flipper I0.

The surface of the flipper ID, as shown in the drawings, is providedwith blades 10a, preferably integrally formed about the perimeter of the body of the flipper and tapering toward the center thereof, thus imparting to the fuel particles not only an outward throw from the discharge end of the tube, but also an angular throw relative to the tube center line. I also form the surface 101) of the flipper, as shown in Fig. 4, so that when the stoker mechanism is at rest any coal particles, which may drop from the inner end of the tube cannot become lodged within the semi-circular arcuate terminus of the easing I4. I also provide the casing I4 with a chute 14b, extending downwardly from its forward terminus 14a to guide any light particles of fuel which might fall when the stoker is at rest, so at such times no fuel particles in the stoker mechanism are exposed to the heat of the fire bed, which particles otherwise might become ignited and cause the ignition of the fuel which is at rest within the feed tube.

It should be noted that the relationship of the flipper III to the inner or discharge end of the fuel feed tube and to the rim of the fire pit is such that the desired flipping action on the fuel particles can be obtained without causing undue agitation of the fuel particles. The plunger makes from 1 to 3 strokes per minute and the fuel displacement along the tube is from one inch to one and one-half inches per plunger stroke. The size of the flipper I0 is such that it can be disposed immediately beneath and adjacent to the discharge end of the tube in such a position that the flipping action thereof will not cause the coal particles to be thrown too violently. The dimensions of the tube in cross section are approximately four inches high and six inches wide and the flipper extends the full width of the tube. The dimensions of the flip- .per thus will be apparent. The speed of the flipper can be varied from three hundred R. P. M. to about nine hundred R. P. M., and the correct speed will be dependent upon the size .of the fire bed and the physical characteristics of 'the fuel to be fed thereto.

It will be apparent from the foregoing description of the flipper, the housings therefor, the adjustable nature of the tube structure extending between the flipper housing and the hopper mechanism, that the flipper can alway be po- I sitioned at the desired point relative to the firemechanism may comprise the conventional type of blower casing I20 and fan IN, the casing I28 being secured to the frame of the motor I23, and the fan I2 I, being secured to one end of the motor shaft I24. Depending from blower casing I28 is a flexible tube I25, which extends downwardly and through a suitable opening I2'I, formed in the ash pit door I 26 of the furnace structure. The blower casing I20 is provided with an air inlet openings. IBI] (Figs. 3 and 4) and the volume of air passing therethrough is regulated by the distance between an adjustable disc I8I and the wall of the casing adjacent the opening I20. The disc is threaded upon a stud I82 carried by the blower casing. The volume of air required is determined by the size of the fire bed, the burning characteristics of the fuel used and the heat delivery demands upon the furnace. Hence, adjustment of the disc I8I toward or away from the air inlet opening of the blower casing will be determined by operating trials of the stoker mechanism at the time of installing the same.

While the disc I8I just described affords some means for controlling the action of the blower upon the firebed when the stoker is in operation, I find it to be advantageous to provide a pneumatically operated damper in the air duct I25. This damper is arranged to open under the infiuence of the. blower and to automatically shut when the blower is not in operation, thereby preventing tne influence of a natural draft upon the flrebed, particularly under Weather conditions when high winds are prevailing. This damper is attached to the ash pit door and may comprise, as shown in Figs. 8, 9, and 10 a tubular sleeve 2I2, of sumcient diameter to conveniently telescopically receive the lower end of an elbow fitting 2I3, the fitting being attached to the end of the duct I25. The sleeve 2I2 may be secured to the ash pit door I26 by bolts 2| 6. The damper comprises a disc-shaped light metal valve 220 and is secured to a pin 22I journalled in the sleeve 2 I2 to swing about an axis disposed below the center thereof. An outer end 22Ia of the pin 22I is bent normal to-the axis of the pin to form an arm upon which is adjustably mounted a weight 225.

The weight acts to swing the valve and cause the edges thereof to abut a shoulder 226, disposed within the sleeve 2I2. I also provide an adjustable stop in the form of a screw 228, mounted on thesleeve 2I2, in the path of the arm 22Ia, whereby the amount of the opening movement of the valve 220, under the influence of the blower, can be adjusted.

The motor I23 may be suitably mounted in an inverted position upon a bracket I28, adjustably secured by bolts I28 to a depending bracket I30, secured to the bottom wall of the fuel feed tube 45 at a position to permit practical driving connections-between the pulley I32, mounted upon one end of the motor shaft I24, and pulley 11, mounted upon the shaft of the gear reduction mechanism. A belt I34 serves to drivingly connect the pulleys I32 and".

My prior experience with stokers of the overfeed type has disclosed that a feed tube carrying fuel cannot be extended into the fire box without attendant difflculties. Under such a condition, the fuel when in the tube has a tendency to coke, thus liberating tar and other sticky components of the average fuel. Likewise, there is always present av flre hazard under such circumstances. It will be apparent from the stoker disclosed in the. drawings that my apparatus for the overfeed stoking of a furnace can be successfully used on different types of domestic heating furnaces and the difliculties and dangers above mentioned are avoided.

Likewise, my improved stoker is practical from a commercial viewpoint, in that regardless of variations in the width of the fire door frame I I, the inner end of the tube and the flipper mechanism can always be adjusted to the proper relationship relative to the rim of the fire pit by reason of the telescoping construction of the flipper housing with the feed tube 45 and by reason of the fact that I provide the fuel feeding tube 45 with the extension tube U10, thus making the installation of the stoker mechanism readily adaptable to various furnace structures. It will be apparent that the only alteration in the structure of the furnace proper would be to swing open the furnace door and to form an annular opening in the ash pit door for the reception of the lower end of the blower duct I25.

My stoker has. been used with anthracite fuel ofthe so-calied pea size, as well as with anthracite culm and bituminous slack coals of both high and low grades, and by reason of the manner in which I control the application of these fuels to the top of theme bed, I have been able to meet widely varying conditions.

It will be apparent to those skilled in the art that the stoker mechanism as illustrated in the drawings may be constructed primarily from sheet metal and preferably ingot iron sheets, which will resist corrosive action, and the entire arangement will be readily responsive to the operative regulation of any of the standard thermostatic control devices now on the market.

I am aware that flipper mechanism for throwing coal onto a fire bed have been proposed heretofore. Such mechanisms have usually been associated with some form of blower means functioning through the fire door. I have devised a flipper mechanism which avoids the use of a blower and I thus avoid the escaping of partially burnt coal dust up the chimney. Protracted testing of my stoker demonstrates the importance of agitating the mass of fuel while removing measured quantities thereof and the ledge principle of fuel escape makes the controlling of the flipping action practical, whereby the powdered portion of the fuel will not be unduly agitated to the extent that the same would be caused to escape up the flue without being burned. The apparatus has been quite successful in stoking a variety of fuels, while maintaining a proper fire bed that will produce very low ash and low fuel losses.

I claim:

1. In a coal feeding mechanism the combination of a coal hopper, a substantially horizontally disposed fuel feeding tube beneath the hopper and provided with A a discharge opening means extending between hopper and tube affording a fuel passageway, a plunger in the tube disposed forwardly of the passageway adapted to feed fuel through the tube, a speed reduction mechanism mounted on one end of the tube, mechanism extending between the speed reduction mechanism and the plunger for imparting limited reciprocating movements to the plunger, an electric motor mounted on the tube, a rotary fuel flipping mechanism mounted below the tube adjacent the inner end thereof and disposed beneath the fuel discharge opening of the tube, and means drivingly connecting the motor to the rotary fuel flipping mechanism and to said plunger actuating mechanism.

2. In a stoker mechanism a unitary structure I to permit the shifting of the stoker mechanism to and from the fire door of a heating furnace, said stoker mechanism having a fuel feeding tube adapted to be projected into the fire door of the furnace and provided with a discharge end, a fuel flipping mechanism adapted and arranged to be disposed at the margin of the fire bed of the furnace and adapted and arranged to flip the fuel inwardly over the fire bed as the fuel falls from the-discharge end of said tube, means for shifting the fuel longitudinally of the tube including a plunger and associated mechanism for reciprocating said plunger, a motor supported by the tube, driving connections between the plunger reciprocating means and themotor and between the motor and the flipping mechanism, whereby the flipping mechanism is operated only when the plunger is being operated, and a blower mechanism associated with said motor and including an.

air duct adapted to extend to the furnace ash pit when's'aid fuel feed tube is operatively positioned with its inner end within the fire door frame of the furnace.

3. In a coal feeding mechanism the combination of a revolvable hopper, a substantially horizontally disposed fuel feeding tube arranged beneath the hopper and provided with a discharge opening, means connecting the hopper and tube and affording a passageway therebetween, a plunger in the tube disposed forwardly of said passageway, a speed reduction mechanism supported by one end of the tube, mechanism to drivingly connect the speed reduction mechanism with the plunger, mechanism to drivingly connect the speed reduction mechanism with the hopper, an

electric motor supported by the tube, a fuel flipper member mounted adjacent the inner end of the tube and disposed beneath the fuel discharge opening of the tube,.said member being rotatable, and means drivingly connecting the motor to the rotatable member and to said speed reduction unit.

4. In a coal feeding mechanism, the combination of a hopper, a substantially horizontally disposed fuel feeding tube beneath the hopper and provided with a dischargeopening, there being a passageway between the tube and the hopper, a plunger in the tube disposed forwardly of the passageway, a speed reduction mechanism, a drive crank mechanism interconnecting the speed reduction mechanism and the plunger, a housing structure supported by the tube adjacent the inner end thereof and disposed beneath the fuel discharge opening of said tube, a rotary fuel flipping mechanism enclosed within said housing, an electric motor supported by the tube, and means drivingly connecting the motor to the fuel flip-' ping mechanism and to the speed reduction mechanism, and said housing comprising a heat insulating means whereby the flipping mechanism may be operatively positioned adjacent a fire bed. 5. In a stoker mechanism a unitary structure adapted to be suspended from above, whereby the entire mechanism may be mounted upon a trolley to permit the shifting of the stoker mechanism to and from the fire door of a heating furnace, said discharge end of said tube, said flipping mechanism including a rotatable member having impellers formed about the circumferential surface thereof, said rotatable member being supported at the inner end of the tube, means for shifting the fuel longitudinally of the tube including a plunger and associated mechanism for reciprocating said plunger, a motor supported by the tube, driving connections between the motor and the plunger reciprocating mechanism and between the motor and saidrotatable flipping mechanism to operate the flipping mechanism only when the plunger is being operated, and a blower mechanism associated with said motor and including a downwardly extending air duct, the lower end of which is adapted to extend to the furnace ash pit when said fuel feed tube is operatively positioned with its inner end within the fire door frame.

6. In a coal feeding mechanism, the combina- 29 tion of a coal hopper, a substantially horizontally disposed fuel feeding tube arranged beneath the hopper and provided with a discharge end having a fuel discharge opening therein, means connecting the hopper and tube and affording a fuel 2 passageway between the hopper and the tube, a

plunger in the tube and operable to shift fuel from said passageway to the discharge end of the tube, a speed reduction mechanism, a. crank mechanism extending between the speed reduction ing tube adapted to be projected into the fire door of the furnace and having a discharge end, a fuel feeding plunger disposed in the tube, a fuel flipping mechanism adapted and arranged to flip the fuel inwardly over the fire bed as the fuel falls from the discharge end of said tube, means for shifting the fuel longitudinally of the tube, a

motor supported by the tube, a driving connection between the motor and the plunger and be- -tween the plunger and the fuel shifting means,

whereby the fuel shifting means is operated only when the plunger is being operated, and a blower mechanism operatively associated with said motor and including an air duct, the lower end of which is adapted to extend to the furnace ash pit when said fuel feed tube is operatively positioned with its inner end within the fire door frame.

HERMAN L. KRAEFT. 

